Building Brains 2 Flashcards
Define ‘pain’. (1)
An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage.
What is the difference between ‘nociception’ and ‘pain’? (2)
Nociception is the detection of noxious events in the environment.
Pain is the emotional response/feelings associated with nociception.
Name three types of afferent sensory nerve fibres in humans. (3)
A beta
A delta
C
Give the relative sizes of Ab, Ad, and C sensory fibres. (3)
Ab - Largest
Ad - Medium
C - Smallest
Which (if any) of the three sensory afferent nerve fibres in humans are myelinated? (3)
Ab and Ad are myelinated.
C are unmyelinated.
Describe the relative conduction velocities and thresholds for the three sensory afferent nerve fibres in humans. (6)
Ab - Fast conduction, low threshold
Ad - Fast conduction, medium-high threshold
C - Slow conduction, high threshold
Which neurotransmitter/s are released by A beta sensory fibres? (1)
Glutamate
Which neurotransmitter/s are released by A delta sensory fibres? (1)
Glutamate
Which neurotransmitter/s are released by C sensory fibres? (1)
Neuropeptides
(eg. substance P, CGRP, somatostatin)
Give the three ‘types’ or stimuli which can cause pain. (3)
- Thermal
- Mechanical
- Chemical
Which modalities do A beta sensory afferent fibres transmit? (3)
- Light touch
- Pressure
- Vibration
Which modalities do A delta sensory afferent fibres transmit? (3)
- Touch
- Temperature
- Sharp pain
Which modalities do C sensory afferent fibres transmit? (4)
- Noxious temperature
- Itch
- Significant pressure
- Dull pain
Describe ‘first pain’. (3)
- Neurones
- Localisation
- Time course
Carried by A delta fibres
Can be accurately localised because nerve endings are bunched together
Begins quickly (high conduction velocity) and goes away quickly (because glutamate rapidly removed from synapse)
Describe ‘second pain’. (3)
- Neurones
- Localisation
- Time course
Carried by C fibres
Location more generalised because nerve endings are spread out
Begins slowly (slow conduction velocity) and lasts longer (as neuropeptides slowly removed from synapse)
True or false (1):
A delta and C fibres are solely afferent neurones which transmit pain signals to the spinal cord.
False - they can have efferent roles too such as vasodilation and plasma extravasation
Which part of the spinal cord receives sensory information? (1)
Dorsal horn
Which dorsal horn laminae receive input from pain specific neurones? (1)
I and II
Which dorsal horn laminae receive input from touch specific neurones? (1)
III and IV
What is the role of lamina V of the dorsal horn? (1)
Integrates sensory input from all sensory neurone types.
True or false (1):
Although pain stimuli are processed by laminae I and II of the dorsal horn, laminae III and IV are also activated in response to a painful stimulus.
True - The touch neurones synapsing on laminae III and IV will also be activated because the high threshold stimulus will have surpassed the low threshold of A beta fibres.
Second order sensory neurones which relay pain signals to the brain mostly arise in which laminae of the dorsal horn? (2)
I and V
To which laminae of the dorsal horn does pain descending modulation usually project to? (1)
II
When first order sensory neurones enter the dorsal horn of the spinal cord, they can synapse onto which two general types of neurones? (2)
- Interneurones
- Projection neurones
Which laminae of the dorsal horn do A delta and C fibres synapse on? (1)
I, II, V
Which laminae of the dorsal horn do A beta synapse on? (1)
III, IV, V
Which lamina of the dorsal horn are A delta neurones MORE LIKELY to synapse on? (1)
a) I
b) II
I
Which lamina of the dorsal horn are C neurones MORE LIKELY to synapse on? (1)
a) I
b) II
II
What is the role of the spinoparabrachial tract in pain? (1)
Forms connections with the amygdala and basal ganglia to play a role in the emotional response to pain.
Apart from the amygdala and basal ganglia, name two other brain structures which may play a role in the emotional perception of pain. How do these structures receive their signals? (3)
Cingulate cortex and insula, which receive signals via the thalamus
How is the periaqueductal grey involved in pain? (1)
Provides descending pain modulation when stimulated.
Give six inputs to the PAG in the context of pain. (6)
- Prefrontal cortex (cingulate and insula)
- Spinal cord dorsal horn
- Amygdala
- Nucleus accumbens
- Hypothalamus
- Locus coeruleus
Which part of the PAG organises descending modulation of pain systems? (1)
Ventrolateral
Which part of the PAG organises autonomic functions? (1)
Dorsolateral
Which part of the PAG projects to the thalamus and frontal cortex as part of the ascending pain pathways? (1)
Rostral
From which sensory fibres does the ventrolateral PAG receive most of its input? (1)
C
From which sensory fibres does the dorsolateral PAG receive most of its input? (1)
A
Describe the descending pain pathway from PAG to spinal cord. (3)
- Ventrolateral PAG
- Rostral ventral medulla (also called nucleus raphe magnus)
- Spinal cord dorsal horn
Describe two ways in which descending signals from the PAG can modulate pain pathways. (2)
- Postsynaptic inhibition of dorsal horn neuronal activity
- Presynaptic inhibition of NT release from nociceptors
Which neurotransmitters can be used in the descending pain pathways? (3)
- Opioids
- Serotonin
- Noradrenaline
What is ‘hyperalgesia’? (1)
Increased responsiveness to a normally noxious stimulus.
What is ‘allodynia’? (1)
Pain or unpleasant sensation evoked by normally non-painful stimulation.
What is ‘spontaneous pain’? (1)
Pain with no obvious immediate cause.
Describe primary hyperalgesia. (4)
Peripheral neuronal changes
to thermal and mechanical stimuli
over a small area surrounding injury
which occurs quickly.
Describe secondary hyperalgesia. (4)
Central nervous system changes
to mechanical stimuli
over a large region surrounding injury
which occurs over a longer period of time.
Describe the effect of intensity and unpleasantness of pain perceived by somebody with a bad mood. (2)
Intensity remains the same but unpleasantness increases.
Describe the effect of intensity and unpleasantness of pain perceived by somebody who is paying less attention/is distracted. (2)
Intensity decreased but unpleasantness is the same.
Which cortical structure is generally regarded as the place where emotional and conscious perceptions of pain are integrated? (1)
Insular cortex
Are limbic system structures cortical or subcortical? (1)
Mixture of both
Give two general roles of the limbic system. (2)
- Respond to emotional, social, and motivational stimuli
- Learning and memory
What are the three components of an ‘emotional state’? (3)
- Autonomic responses
- Subjective feelings
- Cognition
Name the four cortical components of the limbic system. (4)
- Cingulate gyrus
- Parahippocampal gyrus
- Orbitofrontal cortex
- Sensory association areas
Name the 10 subcortical components of the limbic system. (10)
- Amygdala
- Stria terminalis
- Hypothalamus
- Anterior nucleus of the thalamus
- Septal nuclei
- Olfactory bulbs
- Hippocampus
- Fornix
- Nucleus accumbens
- Mammillary bodies
Which lobe contains both the amygdala and the hippocampus? (1)
Temporal lobe
When looking at brain slices, how do you tell the difference between the amygdala and the hippocampus? (2)
The amygdala is smaller and sits more anteriorly.
Name the two main white matter structures connecting the limbic system. (2)
- Fornix
- Stria terminalis
Describe how the hippocampus is connected to other structures in the limbic system. (4)
Connected to mammillary bodies
via the fornix
the mammillary bodies then connect to the anterior thalamus
via the mammillothalamic tract.
Describe the role of the stria terminalis. (3)
Connects the amygdala
to the hypothalamus
and nucleus accumbens.
What is the role of the septal nuclei in the limbic system? (1)
They regulate hypothalamic aggression.
What is the role of the cingulate gyrus in the limbic system? (1)
Cognitive, attentional, and emotional processing.
Give three roles of the hypothalamus relating to the limbic system. (3)
- Autonomic functions (can be related to emotion)
- Endocrine functions
- Aggression
What are the roles of the amygdala in the limbic system? (4)
- Recognising fear
- Acquiring a new fear
- Producing fear responses
- Subjective experience of emotions and pleasure
What is the role of the hippocampus in the limbic system? (1)
It links emotions and memory
What is the role of the parahippocampal gyrus in the limbic system? (1)
Memory encoding
Briefly describe the James Lange theory of emotion. (1)
Physiological status of the body triggers emotion.
Briefly describe the Cannon Bard theory of emotion. (1)
Physiological state of the body and emotions occur simultaneously.
Briefly describe the ‘simple’, or first version of the Papez circuit. (8)
Sensory association cortex
feeds into cingulate gyrus
which passes information to the hippocampus/parahippocampal gyrus to be processed
which passes information to the mammillary bodies (and hypothalamus)
via the fornix
which goes to the anterior thalamic nuclei
via the mammillothalamic tract
which then feeds back into the cingulate gyrus.
After James Papez developed the Papez circuit, it was expanded by Paul MacLean to recognise the importance of which three other structures? (3)
Amygdala
Orbitofrontal cortex
Nucleus accumbens
Briefly describe the pathophysiology of Kluver-Bucy syndrome. (1)
Bilateral temporal lobe lesions
Give three symptoms of Kluver-Bucy syndrome which support the idea that structures important to emotion and memory are housed in the temporal lobes. (3)
- Placidity (poor emotional and fear responses)
- Memory difficulties
- Visual agnosia (inability to recognise familiar objects/faces)
Where is the nucleus accumbens located and what system/s is it part of? (2)
Located within the caudate nucleus.
Part of the basal ganglia and limbic systems.
Name the system which is involved in rewards and motivating behaviours. (1)
Mesolimbic reward system
Which neurotransmitter is involved in mediating the pleasurable aspects of reward? (1)
Dopamine
Describe the mesolimbic reward system (where does it start and where does it project to?). (4)
STARTS:
- Midbrain
PROJECTS TO:
- Amygdala
- Orbitofrontal cortex
- Nucleus accumbens
What would be the effect of giving an animal a lesion in the amygdala, and then implementing fear conditioning? (1)
It will not work - the animal will not be able to acquire the new fear.
What do you predict would happen if you got patients with Urbach-Wiethe disease (calcified amygdala) and showed them pictures of fearful faces? (1)
They would not recognise the fearful expressions.
What is anterograde amnesia? (1)
Inability to produce new memories
What is retrograde amnesia? (1)
Unable to recall memories which have already been formed.
What is meant by ‘declarative’ memory? (1)
Memory for facts and events
What is meant by ‘nondeclarative’ memory? (1)
Memory for procedures, skills, and habits.
Describe the surgery that patient HM underwent. (1)
Removal of the hippocampus and parahippocampal gyrus.
What type of amnesia did patient HM experience? (1)
Anterograde
Name the three parts of the hippocampus from the ‘inside’ to the ‘outside’. (2)
- Dentate gyrus
- Cornu Ammonis (CA)
- Subiculum
What is the role of the entorhinal cortex and what is its location? (2)
- Allows information to enter and leave the hippocampus
- Located in cortex right next to the hippocampus
How many cortical layers does the hippocampus contain? (1)
Three
In which part of the hippocampus do the three cortical layers start to transition to the six cortical layers found in the entorhinal cortex? (1)
Subiculum
Name the three cortical layers found in the cornu ammonis. (3)
- Polymorphic
- Pyramidal
- Molecular
Name the three cortical layers found in the dentate gyrus. (3)
- Polymorphic
- Granular
- Molecular
Describe the polymorphic layer of the hippocampal cortex. (1)
Interneurones and cell axons
Describe the molecular layer of the hippocampal cortex. (1)
Contains dendrites from neurones
Give a definition of LTP (long-term potentiation). (1)
LTP is the cellular basis by which memories are formed and stored.
Name the input pathway of the hippocampus which goes from the entorhinal cortex to the dentate gyrus. (1)
Perforant pathway
Describe the hippocampal pathway associated with LTP. (6)
Entorhinal cortex to dentate gyrus
via perforant path
dentate gyrus to CA3
via mossy fibres
CA3 to CA1
via Schaffer collaterals
Name the fibre type which sends signals from the dentate gyrus to CA3 of the hippocampus. (1)
Mossy fibres
How are signals sent from CA3 to CA1 of the hippocampus? (1)
Via Schaffer collaterals
Where do CA1 neurones of the hippocampus project to? (1)
The subiculum
Name the group of specific cells in the hippocampus that are involved in spatial memory and describe how they function. (2)
Place cells fire depending on the location of the organism in its environment.
How would you predict that rats would perform in the Morris maze if their hippocampus has been lesioned. (1)
Longer latency to escape - they would perform worse.
Name a specific area of the brain in which adult neurogenesis occurs. (1)
Dentate gyrus
In which layer of the dentate gyrus does adult neurogenesis occur? (1)
Sub granular zone
Describe type 1 cells, which play a role in adult neurogenesis. (1)
Undifferentiated stem cells which are dormant.
(Also called radial glial cells)
Name three proteins which are expressed in type 1 neurogenesis stem cells. (3)
- Nestin
- Sox-2
- GFAP
Describe type 2 cells, which play an important role in adult neurogenesis. (1)
Fast proliferating cells
Name two proteins which are expressed in type 2 neurogenesis stem cells. (2)
- Nestin
- Sox-2
Fill in the gaps… (3)
In adult neurogenesis, type 2 cells become committed towards neuronal cell lineage, and are now called ………………………….
These cells develop further to become ………………………
Both of these cell types express the protein ……………………..
- Neuroblasts
- Immature neurones
- Doublecortin
Give six roles of the hypothalamus. (6)
- Emotional responses
- Thermoregulation
- Energy metabolism
- Blood pressure / water balance / electrolytes
- Circadian rhythm
- Reproduction
Describe the role played by the hypothalamus in emotional responses. (1)
Autonomic response to emotional stimuli (eg. sweating)
Is the hypothalamus involved in mainly autonomic or endocrine functions? (1)
Both
Which one of these structures does NOT lie in close proximity to the hypothalamus? (1)
a) Third ventricle
b) posterior commissure
c) Optic chiasm
d) Pituitary gland
Posterior commissure - the hypothalamus lies in close proximity to the anterior commissure
Name the three zones of the hypothalamus.
Roughly how many nuclei does each zone contain? (6)
- Lateral zone (1 nucleus)
- Medial zone (many nuclei)
- Periventricular zone (1 nucleus)
How many nuclei are there in the hypothalamus? (1)
11
Name the eight most important nuclei of the hypothalamus. (8)
- Supraoptic
- Suprachiasmatic
- Preoptic
- Paraventricular
- Dorsomedial
- Lateral
- Ventromedial
- Arcuate
Which hypothalamic nucleus/nuclei is/are involved in regulating blood pressure?
Supraoptic
Paraventricular
Which hypothalamic nucleus/nuclei is/are involved in circadian rhythms?
Suprachiasmatic
Which hypothalamic nucleus/nuclei is/are involved in temperature regulation?
Preoptic
Which hypothalamic nucleus/nuclei is/are involved in energy regulation?
- Paraventricular
- Arcuate
- Ventromedial
- Lateral
- Dorsomedial
Fill in the gaps relating to thermoregulation in the hypothalamus… (2)
The ………….. nucleus regulates temperature via the ………………… system.
Preoptic
Autonomic nervous
How does the skin send temperature signals to the hypothalamus? (1)
Via peripheral thermoreceptors
Name the special neurones in the preoptic nucleus which detect temperature.
Describe the response of these neurones to warmth and cold. (3)
Warm sensitive neurones
Activated when body is warm
Inhibited when body is cold
Which division of the autonomic nervous system is activated when warm sensitive neurones are inhibited? (1)
Sympathetic nervous system
Give three actions of the sympathetic system in regulating body temperature. (3)
- Vasoconstriction
- Brown fat thermogenesis
- Shivering
Which division of the autonomic nervous system is activated when warm sensitive neurones in the hypothalamus are activated? (1)
Parasympathetic nervous system
Give two actions of the parasympathetic nervous system in regulating temperature. (2)
- Vasodilation
- Sweating
Name the hypothalamic nucleus which receives input relating to energy and metabolism. (1)
Arcuate
How is the hypothalamus able to detect signals in the blood stream relating to energy and metabolism which cannot cross the blood brain barrier? (1)
The arcuate nucleus which receives input is surrounded by very low levels of BBB.
Give three stimuli from the body which feed into the arcuate nucleus in order to regulate energy and metabolism. (3)
- Blood glucose/insulin levels
- Ghrelin from GI tract
- Leptin from adipose cells
Which two signals from the body ultimately lead to increased hunger via the hypothalamus? (2)
Decreased blood glucose/insulin.
Increased ghrelin.
Which two signals from the body ultimately lead to increased satiety via the hypothalamus? (2)
- Increased blood glucose/insulin
- Increased leptin
Which hypothalamic nucleus does the arcuate nucleus send signals to to induce hunger? (1)
Lateral nucleus
Via which neuropeptides does the arcuate nucleus signal that hunger should be increased? (2)
- Neuropeptide Y
- Agouti-related peptide
Which hypothalamic nucleus is indirectly involved in feedback loops relating to hunger? (1)
Paraventricular
Which hypothalamic nucleus does the arcuate nucleus send signals to to increase satiety? (1)
Ventromedial
Via which neuropeptides does the arcuate nucleus signal that satiety should be increased? (2)
Pro-opiomelanocortin
Cocaine-and-amphetamine transcript
Which hypothalamic nucleus is indirectly involved in feedback loops relating to satiety? (1)
Dorsomedial
If someone has increased blood osmolarity, are they dehydrated or overhydrated? (1)
Dehydrated
Name the two parts of the hypothalamus (not nuclei) which are able to detect increased blood osmolarity. (2)
- Organum on vasculosum laminae terminalis
- Subfornical organs
The paraventricular and supraoptic nuclei stimulate what to happen in response to increased blood osmolarity? (1)
Vasopressin release by posterior pituitary
As well as receiving information about blood osmolarity, the paraventricular and supraoptic nuclei also receive information about blood pressure via which nerve? (1)
Vagus nerve
Describe the role of the lateral nucleus in water balance. (1)
Increased motivation to drink
Name the cell type which is the output of the retina. (1)
Retinal ganglion cells
The ancestral visual system regulates unconscious visual responses.
Give three output of the ancestral visual system. (3)
- Superior colliculus
- Pretectal nucleus (oculomotor nerve)
- Suprachiasmatic nucleus
The primary visual system provides conscious visual perception.
Name the main nucleus involved in this pathway and describe its location. (2)
Lateral geniculate nucleus
Located in thalamus but in very close proximity to midbrain
Which cells in the retina control the ancestral visual system? (1)
Light-sensitive ganglion cells
Name the two possible streams that can process visual information after it has entered the primary visual cortex. (2)
Ventral and dorsal streams
Describe the location of the ventral stream and its function.
What is its nickname? (3)
- Inferior temporal lobe
- Processes object recognition and memory
- What stream
Describe the location of the dorsal stream and its function.
What is its nickname? (3)
- Posterior parietal lobe
- Object location and positioning
- Where stream
Which nucleus links the visual system with the hypothalamus? (1)
Suprachiasmatic nucleus
What happens to the cyclic rhythmicity of the body if there is a lesion in the suprachiasmatic nucleus? (1)
It halts
Which of these structures is NOT in close proximity to the suprachiasmatic nucleus? (1)
a) Third ventricle
b) Optic chiasm
c) Visual cortex
Visual cortex
Name five areas where pain signals are sent to the brain and briefly describe their roles in pain. (10)
- Brainstem (autonomic changes and spinal cord feedback)
- Thalamus (integration before sending to cortex)
- Somatosensory cortex (conscious localisation and pain recognition)
- Cingulate cortex and amygdala (emotional response)
- Hypothalamus (stress responses and neuroendocrine changes)
Give the order in which the dorsal horn of the spinal cord would respond to each type of sensory fibre. (3)
- A beta
- A delta
- C
The part of the spinal cord where it tapers off is called …………………… (1)
The conus medullaris
Where does the spinal cord end in an adult? (1)
L2
What is the filum terminale and what is it’s function? (4)
A fibrous extension of the pia
coming from the conus medullaris
which stabilises the spinal cord
by anchoring it to the coccyx.
Where do the meninges end in the spinal cord? (1)
S2
Describe the lumbar cistern. (2)
The area of subarachnoid space
below the conus medullaris.
